The present invention relates to a burglar alarm, and in particular to a portable and easily installed burglar alarm unit which is reliable and yet can be manufactured inexpensively. The burglar alarm is mounted on one surface and is attached by a chain to a magnet mounted on a movable second surface. A switch assembly activated by a chain when the second surface moves turns on a bell assembly, which continues ringing thereafter regardless of the force on the chain until a button is moved to the "off" position. A bell assembly which is connected in series with a battery and the switch assembly includes a motor which causes clangers to strike against a bell.
Alarms which can detect unauthorized entry are known in the prior art, but such devices are frequently expensive to manufacture and install. Moreover many prior art burglar alarms must be permanently mounted in one installation, and cannot be applied to a variety of tasks such as guarding a hotel room one day and protecting a brief case the next. Furthermore inexpensive portable alarms tend to be limited in both utility and reliability.
Accordingly, one purpose of the present invention is to provide a better burglar alarm.
Another purpose of the present invention is to provide an inexpensive burglar alarm which is reliable and can be adapted to a variety of tasks.
Still another purpose of the present invention is to provide a burglar alarm which, once activated by an unauthorized entry, will emit a continuing ringing sound until it is deactivated regardless of whether the intruder has abandoned his unauthorized entry.
Other objects and purposes of the present invention will become apparent in the description of the preferred embodiment.